Reliability Based Assessment of Deck Elevations for Offshore Jacket Platforms

2004 ◽  
Vol 126 (4) ◽  
pp. 331-336 ◽  
Author(s):  
Ernesto Heredia-Zavoni ◽  
Dante Campos ◽  
Gallegher Ramı´rez
Keyword(s):  
Reliability Index ◽  
Structural Reliability ◽  
Failure Modes ◽  
Probability Of Failure ◽  
Upper And Lower Bounds ◽  
Series System ◽  
Wave Loading ◽  
System Components ◽  
Storm Wave ◽  
Wave Heights

Structural reliability analyses of fixed marine platforms subjected to storm wave loading are performed to assess deck elevations. Platforms are modeled as a series system consisting of the deck and jacket bays. The structural reliability analyses are carried out assuming dominant failure modes for the system components. Upper and lower bounds of the probability of failure are computed. The variation of the reliability index per bay component as a function of wave height, with a focus on those wave heights that generate forces on the deck, is analyzed. A comparison is given for the deck probability of failure and the lower bound probability of failure of the jacket in order to assess how the deck or the jacket controls the probability of failure of the system. Results are also given for reliability analyses considering different deck elevations. Finally, an analysis of the total probabilities of failure, unconditioned on wave heights, is given.

System Reliability of Existing Jacket Platform in Malaysian Water (Failure Path and System Reliability Index)

2014 ◽  
Vol 567 ◽  
pp. 307-312 ◽  
Author(s):  
V. John Kurian ◽  
Mohamed Mubarak Abdul Wahab ◽  
T.S. Kheang ◽  
Mohd Shahir Liew
Keyword(s):  
System Reliability ◽  
Reliability Index ◽  
Structural Reliability ◽  
Pushover Analysis ◽  
Probability Of Failure ◽  
Jacket Platform ◽  
First Order ◽  
Failure Path ◽  
Reliability Method ◽  
Two Parameters

The objective of this work is to determine the structural reliability of an existing jacket platform in Malaysia, by determining the system probability of failure and its corresponding reliability index. These two parameters are important indicators for assessing the integrity and reliability of the platform, and will point out whether the platform is suitable for continued operation. In this study, pushover analysis is used to determine possible failure paths of the structure, while First Order Reliability Method (FORM) and Simple Bound Formula are used to determine the failure probability and reliability index. Three failure paths of the platform are established. The reliability index of these paths is found with the highest Reliability Indexto be 18.82 from the 315-degree path, while the system reliability index is 9.23. This illustrates that the platform is robust and the chances of collapse is very small.

Probabilistic framework for the assessment of the flexural design of concrete sleepers

2019 ◽  
Vol 234 (7) ◽  
pp. 691-701 ◽  
Author(s):  
Alvaro E Canga Ruiz ◽  
J Riley Edwards ◽  
Yu Qian ◽  
Marcus S Dersch
Keyword(s):  
Cross Sections ◽  
Structural Reliability ◽  
Failure Modes ◽  
Limit State ◽  
Probability Of Failure ◽  
Extensive Study ◽  
Light Rail ◽  
Demand Model ◽  
Reliability Method ◽  
Current Design

An extensive study of the flexural performance of monoblock prestressed concrete sleepers in a light rail system was conducted as part of a research program funded by the Federal Transit Administration. Five consecutive sleepers deployed on the track were instrumented with strain gauges at their critical design cross-sections (center and rail seats) to obtain relevant flexural information during an uninterrupted period of 14 months. Results were compared with the projected design capacities obtained from the application of current design standards, resulting in glaring differences. The current design methodologies were deemed insufficient for the development of optimal design solutions for light rail applications. Furthermore, structural reliability analysis is employed to study the flexural capacity of the sleeper design. A capacity model based on the material and geometric properties of the sleeper design was developed. The demand model was derived from the field flexural data of over 27,000 train passes, fitting this information to predefined probability distributions. Four limit-state functions were defined to represent the typical flexural failure modes. The probability of failure was calculated using first-order reliability method, second-order reliability method, and Monte Carlo simulation. Ultimately, the analysis yielded consistent results for the three methods, showing largely low probability of failure at both design cross-sections under the studied demand level. In conclusion, the sleeper's capacity was higher than the existing field demands, indicating an overly conservative design approach.

Structural Reliability Analysis with Uncertainty-but-Bounded Parameters Based on Meshless Method

2010 ◽  
Vol 163-167 ◽  
pp. 3034-3041
Author(s):  
Wei Zhao ◽  
J.K. Liu ◽  
Qiu Wei Yang
Keyword(s):  
Reliability Analysis ◽  
Meshless Method ◽  
Reliability Index ◽  
Structural Reliability ◽  
Strain Analysis ◽  
Optimization Theory ◽  
Upper And Lower Bounds ◽  
Probability Method ◽  
Structural Reliability Analysis ◽  
Interval Reliability

The structural reliability analysis with uncertainty-but-bounded parameters is considered in this paper. Each uncertain-but-bounded parameter is represented as an interval number or vector, an interval reliability index is defined and discussed. Due to the wide application of the Meshless method, it is used in structural stress and strain analysis. The target variable of requiring reliability analysis is estimated via Taylor expansion. Based on optimization theory and vertex solution theorem, the upper and lower bounds of the target variables are obtained, and also the interval reliability index. A typical elastostatics example is presented to illustrate the computational aspects of interval reliability analysis in comparison with the traditional probability method, it can be seen that the result calculated by the vertex solution theorem is consistent with that calculated by probability method.

scholarly journals Comparative Study of Structural Reliability Assessment Methods for Offshore Wind Turbine Jacket Support Structures

2020 ◽  
Vol 10 (3) ◽  
pp. 860 ◽  
Author(s):  
Abdulhakim Adeoye Shittu ◽  
Ali Mehmanparast ◽  
Lin Wang ◽  
Konstantinos Salonitis ◽  
Athanasios Kolios
Keyword(s):  
Reliability Index ◽  
Structural Reliability ◽  
Reliability Assessment ◽  
Probability Of Failure ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Support Structures ◽  
Structural Components ◽  
Support Structure ◽  
Design Constraints

Offshore wind turbines (OWTs) are deployed in harsh environments often characterized by highly stochastic loads and resistance properties, thus necessitating the need for structural reliability assessment (SRA) to account for such uncertainties systematically. In this work, the SRA of an OWT jacket-type support structure is conducted, applying two stochastic methods to predict the safety level of the structure considering various design constraints. The first method refers to a commercial finite element analysis (FEA) package (DesignXplorer© from ANSYS) which employs direct simulations and the six sigma analysis function applying Latin hypercube sampling (LHS) to predict the probability of failure. The second method develops a non-intrusive formulation which maps the response of the structure through a finite number of simulations to develop a response surface, and then employs first-order reliability methods (FORM) to evaluate the reliability index and, subsequently, the probability of failure. In this analysis, five design constraints were considered: stress, fatigue, deformation, buckling, and vibration. The two methods were applied to a baseline 10-MW OWT jacket-type support structure to identify critical components. The results revealed that, for the inherent stochastic conditions, the structural components can safely withstand such conditions, as the reliability index values were found acceptable when compared with allowable values from design standards. The reliability assessment results revealed that the fatigue performance is the design-driving criterion for structural components of OWT support structures. While there was good agreement in the safety index values predicted by both methods, a limitation of the direct simulation method is in its requirement for a prohibitively large number of simulations to estimate the very low probabilities of failure in the deformation and buckling constraint cases. This limitation can be overcome through the non-intrusive formulation presented in this work.

Reliability Analysis of Portal Frame Based on Space Overall Ultimate Bearing Capacity

2014 ◽  
Vol 501-504 ◽  
pp. 634-639
Author(s):  
Feng Liu ◽  
Shun Cong
Keyword(s):  
Bearing Capacity ◽  
Reliability Index ◽  
Structural Reliability ◽  
Failure Modes ◽  
Ultimate Bearing Capacity ◽  
Finite Element Software ◽  
Portal Frame ◽  
Double Nonlinear ◽  
Improve Reliability ◽  
Nonlinear Numerical Model

This article analyses the reliability of portal frame based on space overall ultimate bearing capacity. A double nonlinear numerical model is established according to the finite element software ANSYS to track the space overall ultimate bearing capacity of the structure and to make clear the failure modes of the structure. The article studies and discusses the reliability of the portal frame based on space overall ultimate bearing capacity, gets the range of the structural reliability index and the sensitive degree of each parameter on the reliability, and presents the measures to improve reliability.

scholarly journals METHOD FOR ASSESSING THE STRUCTURAL RELIABILITY OF NETWORKS WITH UNDETERMINED TOPOLOGY

2020 ◽  
Vol 10 (1) ◽  
pp. 32-35
Author(s):  
Nina Kniazieva ◽  
Alexey Nenov ◽  
Irina Kolumba
Keyword(s):  
Lower Bounds ◽  
Reliability Index ◽  
Structural Reliability ◽  
Structural Characteristics ◽  
Scientific Research ◽  
Network Connectivity ◽  
Upper And Lower Bounds

This paper shows the relevance of the task of assessing the structural reliability of networks with undetermined topology. Proposed is a method for assessing the structural reliability of networks of undetermined topology based on taking into account the basic structural characteristics of the network (the number of nodes and branches, the degree of network connectivity, the maximum allowable rank of paths, and others). To obtain an estimate of the structural reliability for a network of any dimension and any topology, expressions are proposed in the scientific research to determine the number of paths of various ranks, which must be taken into account when calculating the structural reliability index by the upper and lower bounds method.

Vulnerability-Based Design of Sliding Concave Bearings for the Seismic Isolation of Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri ◽  
Phuong Hoa Hoang
Keyword(s):  
Liquid Steel ◽  
Seismic Isolation ◽  
Failure Modes ◽  
Fragility Curves ◽  
Time History ◽  
Probability Of Failure ◽  
Design Parameters ◽  
Economic Losses ◽  
Storage Tanks ◽  
Isolation System

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.

Reliability Analysis of Reinforced Concrete Structural during Construction

2011 ◽  
Vol 71-78 ◽  
pp. 310-314
Author(s):  
Jun Zhao
Keyword(s):  
Reinforced Concrete ◽  
Stochastic Analysis ◽  
Reliability Index ◽  
Structural Reliability ◽  
Reinforced Concrete Structures ◽  
Time Varying ◽  
Calculation Algorithm ◽  
Random Field Theory ◽  
Reliability Calculation ◽  
Practical Engineering

According to random field theory, combined with the construction of the characteristics of reinforced concrete structures, based on the geometric significance of the reliability index, the optimization algorithm of the reliability was established, and the reliability calculation algorithm of reinforced concrete structural during construction is proposed based on stochastic finite element method. Based on a stochastic analysis of the practical engineering, the time-varying laws of the reinforced concrete structural reliability index during construction are concluded.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

Evaluation of the Effect of Yield to Tensile (Y/T) Ratio on the Structural Integrity of Offshore Pipeline by Limit State Design Approach

2006 ◽  
Author(s):  
Gianluca Mannucci ◽  
Giuliano Malatesta ◽  
Giuseppe Demofonti ◽  
Marco Tivelli ◽  
Hector Quintanilla ◽  
...  
Keyword(s):  
Structural Reliability ◽  
Failure Modes ◽  
Structural Integrity ◽  
Limit State ◽  
Minor Effect ◽  
Offshore Pipelines ◽  
Limit State Design ◽  
A Minor ◽  
Probabilistic Failure Analysis ◽  
Failure Probabilities

Nowadays specifications require strict Yield to Tensile ratio limitation, nevertheless a fully accepted engineering assessment of its influence on pipeline integrity is still lacking. Probabilistic analysis based on structural reliability approach (Limit State Design, LSD) aimed at quantifying the yield to tensile strength ratio (Y/T) influence on failure probabilities of offshore pipelines was made. In particular, Tenaris seamless pipe data were used as input for the probabilistic failure analysis. The LSD approach has been applied to two actual deepwater design cases that have been on purpose selected, and the most relevant failure modes have been considered. Main result of the work is that the quantitative effect of the Y/T ratio on failure probabilities of a deepwater pipeline resulted not so big as expected; it has a minor effect, especially when Y only governs failure modes.

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